Treatment of nonmineral fatty matter raffinates



UNITED STATES PATENT OFFICE TREATMENT NONMINERAL FATTY MATTER RAFFINATES Walter J. Hund, Oakland, and Ludwig Rosenstein, San Francisco, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application May 19, 1937,

- Serial No. 143,572

8 Claims.

This invention relates to an improvement in the process for refining fatty matters wherein free fatty acids, mucilaginous material and other undesirable matters are removed by extraction with a nitrogen-containing alkaline refining agent, such as amines, alkylolamines, ammonia, etc., the extractants being anhydrous or in aqueous admixture and used individually or as a mixture with other solvents.

More specifically, it consists in removing the last traces of the refining agent from the treated fatty matter by washing with a weakly acid aqueous solution of an acid-acting agent.

According to the present practice, the fatty matter, which may be of animal, vegetable or synthetic origin is extracted in the liquid phase with a suitable amount of an alkaline nitrogencontaining refining agent, such as, for example, ethanolamine or ethylene diamine. Other suitable agents are described in U. S. Patents Nos. 1,900,132 and 1,885,859. The free fatty acids, mucilaginous matter, certain coloring bodies, anti-oxidants, aldehydes and other undesirable materials are substantially removed in the extract phase while the vitamine content of the fatty matter is unaltered. The small amount of refining agent remaining in the fatty matter is extracted with successive amounts of water. The first water washes are very effective and remove the major part of the refining agent without difficulty. The remaining trace of refining agent which exists in the raffinate predominantly in the form of a soap is very difficult to remove even with repeated water washing. A conventional method used to remove the last traces of refining agent is to blow the heated raffinate with an inert gas under reduced pressure. This method has the objections of requiring costly equipment and considerable operating expense.

The presence of even traces of such soaps may be objectionable, if they impart a disagreeable taste, lower the resistance to rancidification, promote discoloration, orpromote sludge formation on aging.

We have found that if, in the removal of the last traces of refining agent by water washing, the last water wash is replaced by a wash with an aqueous weakly acid solution, as, for example, a dilute solution of hydrochloric acid, that the refining agent is liberated from its soap and completely removed while the free fatty acid content of the rafiinate is unaltered.

Any material which is at least moderately soluble in water, substantially insoluble in the fatty matter in question and shows an acid reaction when in aqueous solution, is a suitable acid-acting agent. The most important members of this group are of mineral origin and include the halogen acids, sulfuric acid, phosphoric acid and acid- V acting salts such as acid sulfates, ZnClz, ZnSO4, 5 FeCla etc. Certain organic acids, as for example citric, lactic and acetic acid have been found to be operative. In general, we use those acid-acting agents in concentrations which, during the washing step, are capable of causing the 10 liberation of the alkaline refining agent from its soap.

The reaction is nearly quantitative, is substantially complete in a very short time (which is dependent upon the degree of mixing), and does not require special conditions as regards temperature, pressure, etc.

As is the case with ordinary water washing, the acid washing is preferably executed while the fatty matter is in the liquid state. This requires '20 slightly elevated temperatures when dealing with fats, waxes, resins, etc., which are solid at ordinary temperatures. Elevated temperatures reduce the viscosity of the fatty matters and thereby the rate of phase separation, which is, in 2 many cases, advantageous.

Since the reaction is nearly quantitative, approximately the stoichiometric amount of acid is preferably used. A moderate excess of acid is, however, not detrimental. It is obvious that only '30 small quantities of acid are required and that no acid need be wasted.

The term fatty matter as used heretofore and in the claims is intended to comprehend the general class of organic oils, fats, waxes, and resins of animal, vegetable, or synthetic origin which may be successfully refined through use of the above mentioned refining agents. Examples of the same are sesame oil, herring oil, cottonseed oil, sardine oil, coconut oil, cocoabuto ter, palm oil, carnauba wax, beef tallow, spermaceti, bush kauri, codliver oil, etc.

The term rafiinate designates a fatty matter substantially freed by previous treatment of all undesirable constituents capable of being re- 45 moved by the refining agent in question.

As illustrative of the effectiveness of our invention, we offer the following experimental results, which, it is to be understood, are not to be regarded as limiting the scope of the invention 50 as regards material treated, acids used, time of contact, proportions of matter or the like.

A corn oil raffinate, refined by the use of ethanolamine and washed twice with water, contained 0.032% ethanolamine and 0.103% free 5 fatty acid (as oleic). Only by repeated washing and filtering in the laboratory under uneconomic conditions could these values be finally reduced to 0.007% ethanolamine and 0.053% free acid (as oleic). Portions of the well washed raffinate were thereupon washed for two minutes with 4% by volume of 0.03 normal acid solutions and filtered. This corresponds to 10% acid in excess over the stoichiometric requirement. The results are shown in the following table:

Percent Percent Acid solution used ethanolamine ggeozliig The striking reduction of the ethanolamine content and the constancy of the free fatty acid content are self-evident.

Our improved process offers distinct advantages since through the execution of our invention we are able, with little expense, to remove the before-mentioned undesirable soaps from fatty matters and thereby improve their quality as regards taste, color stability, etc., without affecting the content of free fatty acid.

We claim as our invention:

1. In a process for the refining of fatty matters with a nitrogen-containing alkaline extractant, the steps of first water-washing the raflinate obtained by the main extraction until substantially no free extractant is included therein and subsequently washing the ralfinate with a minor volume of a dilute aqueous solution of an acidacting agent at least stoichiometrically equivalent to the soaps present in the treated raflinate whereby the extractant combined as soaps is liberated and simultaneously substantially removed from the fatty matter.

2. In a process for the refining of fatty matters by extracting with an amine, the steps of first Water-washing the rafiinate obtained by the main extraction until substantially no free amine is included therein and subsequently washing the rafiinate with a minor portion of a dilute aqueous solution of an acid-acting agent at least stoichiometrically equivalent to the amine soaps present in the treated rafiinate whereby the amine combined as soap is liberated and simultaneously substantially removed from the fatty matter.

3. In a process for the refining of fatty matters by extracting with an alkanolamine, the steps of first water-washing the rafiinate obtained by the main extraction until substantially no free alkanolamine is included therein and subsequently Washing the raffinate with a minor portion of a dilute aqueous solution of an acid-acting agent at least stoichiometrically equivalent to the alkanolamine soap present in the treated rafiinate whereby the alkanolamine combined as soap is liberated and simultaneously substantially A; moved from the fatty matter.

4. In a process for the refining of fatty matters by extracting with an ethanolamine, the steps of first water-washing the rafflnate obtained by the main extraction until substantially no free ethanolamine is included therein and subsequently washing the raflinate with a minor portion of a dilute aqueous solution of an acid-acting agent at least stoichiometrically equivalent to the ethanolamine soaps present in the treated raffinate whereby the ethanolamine combined as soaps is liberated and simultaneously substantially removed from the fatty matter.

5. In a process for the refining of fatty matter with a nitrogen-containing alkaline extractant, the steps of first water-washing the raflmate obtained by the main extraction until substantially no free extractant is included therein and subsequently washing the rafiinate with a minor volume of a dilute aqueous solution of a mineral acid at least stoichiometrically equivalent to the soaps present in the treated rafiinate whereby the extractant combined as soaps is liberated and simultaneously substantially removed from the fatty matter.

6. In a process for the refining of fatty matter of fish origin by extracting with an ethanolamine, the steps of first water-washing the rafiinate obtained by the main extraction until substantially no free ethanolamine is included therein and subsequently washing the rafiinate with a minor portion of a dilute aqueous solution of a mineral acid at least stoichiometrically equivalent to the ethanolamine soaps present in the treated raffinate whereby the ethanolamine combined as soaps is liberated and simultaneously substantially' removed from the fatty matter.

7. In a process for the refining of sardine oil by extracting with an ethanolamine, the steps of first water-washing the rafiinate obtained by the main extraction until substantially no free ethanolamine is included therein and subsequently washing the rafilnate with a minor portion of a dilute aqueous solution of a mineral acid at least stoichiometrically equivalent to the ethanolamine soaps present in the treated rafiinate whereby the ethanolamine combined as soaps is liberated and simultaneously substantially removed from the sardine oil.

8. In a process for the refining of sardine oil by extracting with an ethanolamine, the steps of first water-washing the raffinate obtained by the main extraction until substantially no free ethanolamine is included therein and subsequently Washing the rafiinate with a minor portion of a dilute aqueous solution of hydrochloric acid at least stoichiometrically equivalent to the ethanolamine soaps present in the treated rafiinate whereby the ethanolamine combined as soaps is liberated and simultaneously substantially removed from the sardine oil.

WALTER J. HUND. LUDWIG ROSENSTEIN. 

